Continuous invert sugar process

ABSTRACT

A syrup containing invert sugar and sucrose, preferably a 50-50 mixture, is made on a continuous basis by mixing an acid with a solution of sucrose, allowing partial inversion to take place in a first inversion zone, passing the partially inverted sugar syrup into a second inversion zone having an automatic level control wherein the optical rotation of the sugar syrup leaving the second zone is measured by a polarimeter and the flow of material from the first zone to the second zone is controlled, based on the polarimeter reading of the effluent from the second zone. After leaving the second zone, the solution is neutralized so that inversion does not proceed further.

United States Patent [72] Inventors Richard N. Prince Crockett; Asa O.Maylott, Concord, both of Calif. [21] Appl. No. 804,628 [22] Filed Mar.5, 1969 [45] Patented Jan. 4, 1972 [73] Assignee California and HawaiianSugar Company [54] CONTINUOUS INVERT SUGAR PROCESS 3 Claims, 2 DrawingFigs.

[52] US. Cl 127/41, 23/230 A, 23/253 A, 127/30 [51] Int. Cl Cl3k l/08,C131: 3/00, CO7c 47/18 [50] Field of Search 127/29, 30, 41; 23/230 A,253 A; 235/15 1.12

[56] References Cited UNITED STATES PATENTS 498,000 5/1893 \Vohl et a1.127/41 1,402,615 1/1922 Hughes et a1. 127/41 2,459,991 1/1949Capdevielle....... 127/41 X 3,480,476 11/1969 Abbott 127/41 X FOREIGNPATENTS 687,668 2/1953 Great Britain 127/41 WHITE SUGAR OTHER REFERENCESSugar Technology Department, Notes on the Manufacturing of Cane SugarSyrups." Hawaiian Planter s Record 47: 97- l 12 (1943) Newton, LiquidSugar Operation and Automation at the Brockfield Distribution Terminal"Chem. Abs. 4722q 1963) Spencer et al., Cane Sugar Handbook pp. 409- 15.NY. (1963) Wiley & Sons Primary Examiner-Morris O. Wolk AssistantExaminer-D. G. Conlin Attorney-Eclthoff and Hoppe ABSTRACT: A syrupcontaining invert sugar and sucrose, preferably a 5050 mixture, is madeon a continuous basis by mixing an acid with a solution of sucrose,allowing partial inversion to take place in a first inversion zone,passing the partially inverted sugar syrup into a second inversion zonehaving an automatic level control wherein the optical rotation of thesugar syrup leaving the second zone is measured by a polarimeter and theflow of material from the first zone to the second zone is controlled,based on the polarimeter reading of the effluent from the second zone.After leaving the second zone, the solution is neutralized so thatinversion does not proceed further.

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CONTINUOUS INVERT SUGAR PROCESS SUMMARY OF THE INVENTION In manyapplications of sugar, it is highly desirable to provide a syrup whichcontains both ordinary sugar and invert sugar. For instance, byproviding an approximately 50-50 mixture of the two sugars, one achievesabout maximum solubility so that a minimum of water is present ascompared with syrups containing other proportions of invert sugar andsucrose. Such highly concentrated solutions are highly desirable sincethe minimum amount of water need be shipped and also in manyformulations, such as in candy making, where ultimately the watercontent must be reduced to a very low level, it is obvi ously moreeconomical to start with the highest possible concentration of sugar.Additionally, a 50-50 mixture of invert sugar and sucrose forms a syrupso concentrated that the growth of microorganisms is inhibited, so thatthere is essentially no spoilage problem.

Heretofore in preparing such sugar solutions it has been customary toprepare the solution on a batch basis by blending invert syrup withmelted granulated syrup. In accordance with the present invention, acontinuous process is provided by a unique system of process control sothat ordinary granulated sugar is rapidly and continuously convertedinto a sugar syrup containing both invert sugar and ordinary sugar.Preferably, for the reasons given above, the finished syrup containsabout 50 percent of each sugar, said syrup containing about 77 percentsolids (76.2 percent rds). This, of course, is an optimum productcontaining the maximum percentage of sugar which will not crystallize atnormally encountered temperatures and which will not ferment. However,it will be obvious to those skilled in the art that the process of thepresent invention is capable of yielding sugar syrups containing otherpercentages of the two sugars as well as syrups having a lesser totalsolids content.

In inverting sugar it is important to provide close control of thereaction and particularly to provide for slowing the reaction downrapidly when the desired degree of inversion is achieved.

Thus, an object of the present invention is to provide a process formaking a 50-50 sucrose-invert sugar syrup containing about 77 percentsolids.

Another object of this invention is to provide a continuous processwherein such a syrup can be made from ordinary sucrose.

Still another object of this invention is to provide a sim plifiedprocess largely having automatic process controls, requiring the minimumamount of labor or other supervision.

Another important aspect of the invention is to provide a preciseprocess control system which is rapid to respond.

In general, the objects of the present invention are achieved bycarrying out the inversion in one or more zones wherein the percentageof inversion of the efiluent is measured and used to control the amountof fresh material flowing into the zone. Preferably the inversion iscarried out in two separate zones wherein a first zone is used as aprimary inversion zone by mixing therein melted sucrose and acid. Theinversion is carried on in the first zone under automatic control tosomething less than the ultimate desired inversion and the solution isthen passed to a second inversion zone having an automatic level controlwherein the reaction continues. An automatic polarimeter is provided onthe outlet of the second inversion zone and the flow of material intothe second inversion zone is controlled by the amount of invert sugar inthe effluent. Since flow out of the zone is controlled by an automaticlevel valve, it is obvious that if the material is introduced into thesecond zone at a high rate, the residence time will be short and theamount of additional inversion will be low and vice versa. Thus, controlof the rate at which liquid is added to the second tank provides aconvenient way to control the degree of inversion. Since this type ofcontrol provides for an immediate flow of fresh dilution material intothe zone, precise control is achieved and the reaction does not gobeyond the desired point. After leaving the second zone, the sugar syrupnow being at the desired degree of inversion is neutralized whereupon itcan be cooled and stored.

The reaction could be done in a single tank or it could be carried outin three or even more tanks. In general, the larger the number of tanks,the greater the reaction rate and thus the throughput for the totalvolume involved. As the number of tanks increases, the control equipmentbecomes more expensive and two reaction tanks has been found to be aneffective compromise between tank utilization and the expense of controlequipment.

BRIEF DESCRIPTION OF THE DRAWING FIGS. IA and 1B of the drawing are aflow diagram of a plant embodying the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS A melted sucrose stock having asugar content of about 75.2 rds is first prepared. For this purpose,water is introduced through line 2 and mixed with steam through line 4to produce a hot water stream 6, a portion of which is introducedthrough line 8 to premelt manifold 10 where white sugar is added frombins 12. A screw conveyor 14 moves the wet sugar into melt column 16where additional water is added through line 18 to maintain a density ofapproximately 76.2 rds. Column 16 is equipped with an agitator 20 and bythe time the sugar has reached the bottom of the column, it has beencompletely dissolved or melted. A small amount of water is now addedthrough line 22 to reduce the density to about 75.2 rds and the meltedsucrose of the desired density is passed through line 24 into a holdingtank 26.

The melted sucrose is passed into a primary inversion tank 28 and at thesame time hydrochloric acid is added through line 30 from an acid drum32 which is controlled by a pH controller 34 to maintain a pH in thetank 28 from about 1.7 to 2.3 or preferably about 2.1. Tank 28 isprovided with an agitator 29 and a steam jacket 31. An automatic levelcontrol valve 36 maintains the desired level in tank 28. The residencetime in the primary inversion tank is about 15 to 40 minutes and thetemperature is maintained at about 72 C. The reaction rate could beincreased by lowering the pH and/or raising the temperature, but it isimportant that the rate not be too high as this could produce a coloredproduct. During this period from 30 to 35 percent of the sugar isinverted.

The material in tank 28 is now passed through line 38 into a secondaryinversion tank 40. The secondary inversion tank 40 is substantially thesame as the primary inversion tank 28 and output from this tank is takenthrough line 42 and the rate at which the material flows out iscontrolled by a level valve 44. In other words, a constant level will bemaintained in the tank 40 and the amount of material flowing out of thetank will depend upon the amount flowing into it. The outlet line 42 isprovided with a polarimeter 46 which is used to control inlet valve 48in line 38. The polarimeter is set so that if the amount of invert sugarleaving through line 42 is less than 50 percent, valve 48 will closedown, causing a greater holding time in tank 40 and this condition willprevail until the invert content has been brought up to the desired 50percent. On the other hand should the invert content go over 50 percentinvert sugar, then valve 48 would open more, bringing in more of thelower invert solution and allowing a shorter residence time and thus theamount of inversion taking place in tank 40 would be reduced to theextent necessary to reduce the fluent down to 50 percent invert sugar.

When the material is withdrawn through line 42 it is passed to the tank50 where sodium carbonate is added through line 52 from tank 54. Thesodium carbonate neutralizes the acid, causing the inversion reaction toimmediately cease. According to the preferred operation of the process,the syrup in tank 50 contains approximately 50 percent sucrose and 50percent invert sugar and has 77 percent solids (76.2 rds). The sugarsyrup is withdrawn through line 54, passed through a heat exchanger 56where it is cooled and then may be withdrawn for use through lines 58 or60 or stored in tank 62.

It will be apparent that a novel process has been provided which islargely automatic in operation whereby one can prepare invert sugarsolutions on a continuous basis. Although the invention has beendescribed in terms of providing a 50-50 invert-sucrose syrup of highsolids content, it will be apparent to those skilled in the art thathigher or lower percentages of inversion can be obtained if desired andalso that less concentrated syrups can be produced by the continuousprocess described.

We claim:

1. In a continuous process for converting sucrose at least partly toinvert sugar wherein there are at least a first and a second inversionzones for converting sucrose to invert sugar, the improvement comprisingproviding a continuous process for producing a predetermined amount ofinvert sugar in the product by maintaining a constant level of sucroseand invert sugar in the second inversion zone continuously measuring theinvert sugar content ieaving the second inversion zone, employing theamount of said inversion to regulate the flow of sucrose and invertsugar entering the second inversion zone, said flow being inverselyproportional to the residence time in the second inversion zone, thuscontrolling the amount of inversion in the second inversion zone.

2, The process of claim I wherein the sugar is converted from sucrose to3035 percent of invert sugar in the first inversion zone and isconverted to about a 50-50 mixture of sucrose and invert sugar solids inthe second inversion zone.

3. The process of claim I wherein the final product has about 77 percentsolids.

l I i

2. The process of claim 1 wherein the sugar is converted from sucrose to30-35 percent of invert sugar in the first inversion zone and isconverted to about a 50-50 mixture of sucrose and invert sugar solids inthe second inversion zone.
 3. The process of claim 1 wherein the finalproduct has about 77 percent solids.